Tuscaloosa Sand, "geopressured" zones could raise nation's supply
The night of Aug. 13 was one that Lucy Parlange, wife of a plantation owner near New Roads, La., will never forget. She recalls: "We were sitting up here on the gallery, when we heard this terrific sound, like a sonic boom. I thought the air conditioner in the kitchen had blown up." What had really blown was a giant natural-gas well that probably will make Lucy and her husband, Walter Parlange, royalty rich.
The well's importance goes far beyond that. Its discovery indicates that a major new gas-exploration effort in the Tuscaloosa Sand geological formation of southern Louisiana is hitting pay zones. That promises new production not only for Louisiana but for an energy-hungry nation that counts natural gas as both its cleanest-burning and most critically scarce fuel. Last week the Louisiana Office of Conservation estimated that gas reserves in the Tuscaloosa Sand may reach 3 trillion cu. ft. That would be equal to 86% of last year's production in Louisiana, which leads the nation in gas output, and 18% of annual consumption in the whole country. To its discoverers that much gas would be worth $5.5 billion at existing wellhead prices on Louisiana's intrastate free market.
Moreover, as TIME Correspondent Robert Parker reported after a tour of the area, an even bigger potential bonanza lies near by, in the "geopressured" zones full of hot, salty water and dissolved gas that underlie thousands of square miles along the Gulf Coast. David Lombard, a physicist for the Department of Energy, asserts: "If everything works, we will have as a goal to produce 2 trillion cu. ft. of gas a year from geopressured zones by the year 2000." That would equal 10% of the present U.S. gas consumption.
The Parlange well extended the known limits of the Tuscaloosa Sand, which is named for the Alabama county where it crops to the surface. In Louisiana, the "trend" (main potential gas-producing formation) lies four miles beneath the green bayous and sugar-cane fields and stretches 200 miles from Lake Pontchartrain to the Texas border. Because of its depth, high temperature and geological history, the Tuscaloosa Sand has produced mostly gas, very little oil.
Exploration crews have been probing the Tuscaloosa Sand since the early 1960s, but the gas proved elusive. Formed 65 million years ago in northern Louisiana and swept southward by ancient rivers, it lay hidden under a layer of limestone that distorted the echoes of shock waves by which geologists map underground formations. But a Chevron geologist's hunch, confirmed by tests using computer techniques, led prospectors to a swampy field on the Parlange plantation. When the drill bit spun into a zone of extreme pressure 21,345 ft. down, the gas and steam crushed the well casing, ripped out a blowout preventer at the top of the well and blew out of control.